Updates to rxjava-libgdx dependencies and new functionality

This pull request contains several updates to the rxjava-libgdx library to make it up to date with the new versions of the dependencies and add some missing functionality.

* Updated to work with rxjava 0.19 and libgdx 1.2
* Moved tests to src/test/java
* Added HttpRequest observable creation
* Refactored input and contact events
* Added lifecycle events